1. Field of the Invention
THIS invention relates to a method of mounting a hard insert such as a button in a cutting tool such as a drill bit and to a cutting tool formed by the method.
2. Description of Background Art
Various kinds of drill bits and other cutting tools are known in which hard buttons of tungsten carbide or other hard material are mounted in order to increase the durability of the bits. For example, knock-off drill bits which are intended to fit onto the tapered end of a drill rod generally comprise a cup-shaped body which defines a tapered, generally frusto-conical socket which fits onto the end of the drill rod, and have several hard buttons mounted in seats in a head portion of the body.
It is conventional to mount the buttons in their seats by brazing. In this case, the buttons are made somewhat smaller than the seats. It is also known to heat shrink the buttons into their seats. In this case, the buttons are sized exactly with respect to their seats. The drill bit is heated, the buttons are inserted into their seats, and the drill bit is cooled, so that the buttons are held firmly in their seats.
It is an object of the invention to provide an alternative method of mounting buttons in a drill bit.